


Bloodtype

by MakeItVoid



Series: Arcobaleno Associations [6]
Category: Katekyou Hitman Reborn!
Genre: Adult Arcobaleno, Alpha!Arcobaleno, Alternate Universe - ABO, Alternate Universe - Canon Divergence, Hesitant smut, Humour, Mentions of Sex, Multi, Omega!Skull, Omega?Reborn, Omegaverse, Pretty sure omegas don't look like Fon, Skull wants a harem damn it, Smut
Language: English
Status: In-Progress
Published: 2019-06-17
Updated: 2020-04-22
Packaged: 2020-05-13 14:33:10
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 2,917
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19253122
Author URL: https://archiveofourown.org/users/MakeItVoid/pseuds/MakeItVoid
Summary: Oneshots of ABO humour.Chapter 1: Skull is a perfectly awesome omega and all the other Arcobaleno are alphas. Skull can’t be the only person confused as to why he doesn’t have a harem yet.Chapter 2: Reborn is an omega but no one believes him because what kind of omega looks like death itself.Chapter 3: Tsuna never really understood the whole concept of smell and why so many other Omegas lost their minds. (And then Reborn regrows into an adult and presents as an Alpha.)





	1. Harem

**Summary for the Chapter:**

> Skull is a perfectly awesome omega and all the other Arcobaleno are alphas. Skull can’t be the only person confused as to why he doesn’t have a harem yet. It's right there! Why is no one cooperating?

“So,” Skull says.

Colonnello does a full body flinch and whips around, clutching the ear Skull whispered into like some old fashioned maiden caught in only her night gown. “What the fuck?” Colonnello turns sideways on the couch. “How long have you been here?”

“Oh, you know,” Skull muses.

Three hours, hoping that Colonnello or Lal -maybe both- would spontaneously have a rut while they sparred in the backyard and Skull could jump in to save the day.

Skull vaults over the back of the couch and bounces when he lands. “So, hey.”

“No.”

Skull pauses. “Alright. However-“

“A hundred percent no. Get away from me.”

Skull whines, slumping down. “You haven’t even heard what I want to ask.”

Colonnello grimaces. “I can smell your pre-heat pheromones. No. Put on some deodorant.”

Skull squints at him. “Am I…tempting you?”

“You smell like instant noodles. Reheated. In the microwave.”

Lal comes down the stairs, drying her hair on a towel. “What is that smell? Did you burn somethi-“ She stops. “Oh. Hello, Skull.”

* * *

“I need you to do something,” Skull says, hands clasped together, peering up at Viper from where he’s kneeling on the ground. “I need you to fuck me.”

“I would rather pay you to leave my house.”

Skull shakes his hands around for emphasis. “Okay but let’s pretend. We don’t have to, just lie for me.”

“Please leave.”

* * *

Skull bounces where he sits on the cold, hard metal of the empty bank vault he was shoved into.

Verde eyes him warily from the other side. “I want you to know that I take supplements specifically to not be affected by an omega’s heat.”

Skull stops bouncing. “Aww, Verde.”

The door opens anyway and Fon peers inside at the hostages. “Ah, found you. Everything has been taken care of.”

“Thank God,” Verde sighs in relief.

He steps out and slams the door shut in Skull’s face, only to come back with some kind of fire hydrant thing that stops the heat dead. Skull pouts particularly hard during the debrief.

* * *

Skull bursts into the door, dropping the picklocks and kicking it shut. He runs up the stairs while stripping himself so he bounces off a couple of walls, knocks some stuff over. Doesn’t matter because he smells a delicious alpha in rut.

The bedroom door opens before Skull can kick it in and a Fon wearing only his pants frowns at him, hair messed up and bite marks scattered over his shoulders and neck.

Skull throws his arms up. “What the hell, Fon? This was my chance!”

Reborn, reduced to non-verbal snarling, still has good enough aim to pelt Skull in the face with a vibrator.

Skull is thrown out onto the street and Fon kindly tosses his clothes out after him.

* * *

“Oh no,” Skull slurs when Lal drags the other woman off him. “Guess I’ve been drugged. Oops. I suppose one of you is just going to have to-“

Verde easily pulls out a syringe. Skull tries to weakly crawl away but damn those drugs are actually pretty strong. It’s still nothing compared to Verde’s antidote.

* * *

Mammon snaps their fingers a few times. “Skull. Skull, are you even paying attention?”

Skull sighs, loud and long before lifting his head from the table and propping it on a hand. “Am I that undesirable?”

“Yes,” Reborn deadpans.

Lal smacks him on the thigh. “No, you just sniff around where you’re not wanted.”

Reborn raises an eyebrow. “How is that any nicer than what I just said?”

“I actually just hit you because I like it.”

Reborn smirks and leans in for a filthy kiss, Lal digging her nails into his inner thighs.

Skull sighs again, even louder and longer. “What part of me-“

“All of it,” Reborn mutters around the kiss and then moans when Verde leans in from behind and bites into the hitman’s neck.

Skull flops back into his chair. “Someone other than Reborn; what part of me is such a turn off?”

Fon hums. “I wouldn’t put it like that. It is simply a matter of preference.”

“Well what part of me don’t you prefer?”

Fon shrugs. No one else is paying attention because they’ve gravitated towards what is the beginnings of yet another orgy that Skull isn’t invited to.

Skull huffs in annoyance and settles in to watch.

* * *

The Arcobaleno genuinely don’t understand what makes them view Skull as a complete non-entity in terms of lust. It’s not that they look at him in disgust or think he’s not their type. It is quite purely instinct that makes them push him away.

Then Aria is born and it all slots into place. Because now there’s a child to care for and Skull -cute, innocent and bubbly little Skull- no longer triggers strange parental instincts in the Arcobaleno. Skull was always toeing the line between a potential mate and a dependant, so he ended up confusing everyone.

Having a genuine child means Skull is firmly pushed into the mate category.

They still don’t fuck him though because it’s funnier this way.


	2. But Seriously

**Summary for the Chapter:**

> Reborn is an omega but no one believes him because what kind of omega looks like death itself.

It's loud, like it always is with the Vongola. Except this dinner includes all of the allies because Xanxus' birthday party was this morning and Tsuna refused to not celebrate with absolutely everyone.

Xanxus is huffy -homicidal- about having to put up with it. Whenever he rips off the stupid 'Birthday Boy' badge the Varia forced on him, it returns when people keep sneakily pinning it back on to his clothes.

Xanxus is edging the line between tolerant and actually getting upset so the normal seating arrangement that everyone's fallen into has been switched up. Reborn is firmly on the left with Squalo on the right and Skull is across because he can take a hit.

Bester is under the table like always when Xanxus eats, lounging across several people's feet and demanding food from anyone within biting distance. Xanxus glances over when even Reborn bends down, leaning towards the Varia boss to feed Bester a piece of venison.

The back of Reborn's collar pulls away from his neck with the motion and Xanxus immediately notices the thick bandage wrapped around the man's nape. It supresses scent, Xanxus knows at least that much, but Alphas don't have scent glands there.

"Why do you have a scent collar?" Xanxus asks, slumped back in his chair and sipping wine.

Reborn straightens up and wipes his hand on a napkin because Bester slobbers. "I need it," Reborn admits.

"Why?" Squalo chimes in from the other side of Xanxus.

Reborn blinks. "Pheromones from an omega also include any and all emotions we have, not like an Alpha who only gives off the stronger emotions they feel. I have good control but it's easier to use a collar."

Several people have tuned in to the discussion by now and Kikyo, a bit further down the table next to Byakuran, leans forward to better see the hitman. "I thought Alphas didn't have scent glands on their neck."

"They don't," Reborn says simply. "I'm an omega."

There's a pause and Spanner, down the other side of the table, tilts his head a bit. "I don't understand the joke."

"It's not a joke," Reborn says slowly like he's speaking to a child.

Squalo scans the hitman's body. "You don't look like an omega."

Reborn turns fully in his chair to stare the swordsman down. "This is not an argument. I'm not discussing this with you, I'm flat out telling you that it's a fact I'm an omega."

"I'm pretty sure you're not," Byakuran chimes in.

Reborn sucks in a breath and leans back in his chair like he's trying to get away from the stupidity. "Someone -anyone- help me. Skull, please, explain to them."

Skull flashes a grin. "Yeah, Reborn is an omega." Skull squints at Reborn from how hard he's smiling. "Like Fon is."

Reborn narrows his eyes at the lackey but everyone listening in turns to Fon down the left of the table. Fon, with his rippling muscles. Fon, with his knowledge of over a hundred schools of martial arts. Fon, completely willing to using said rippling muscles and knowledge to beat the shit out of anyone who dares to ask for a spar.

"Voi!" Squalo bellows at Fon, easily cutting over the loud chatter. "Bigger Hibari, are you an omega?"

Fon pauses at the sudden attention, tea halfway raised to his mouth, and smiles serenely. "Why yes, I am." Fon's easy countenance and wide eyes make him look a bit air-headed and definitely not like he's being serious.

"Fon," Reborn snaps in annoyance.

Fon sips his tea.

Kikyo looks at Reborn again, along with the mass of people dragged into this conversation from Squalo's loud bellow. "I really don't think you're an omega."

Reborn sighs. "I don't care."

"You smell like an Alpha," Adelheid points out from within a cluster of Simon. "If you truly are an omega then why do you hide it?"

"I don't hide it," Reborn explains. "I'm very open about it, but I use a collar to hide the invasive aspects of pheromones and I spend too much time with Alphas so their scent clings to me."

Xanxus, no hesitation, leans over and buries his face into Reborn's neck, breathing in deeply. Lawfully, the Arcobaleno alphas can kill Xanxus for that. As it is, the strongest just watch on in amusement because this is really the only time Reborn doesn't immediately get his way.

Xanxus pulls back with a frown. "You do smell like other people."

"Thank you-"

"But you could still be an alpha."

Reborn rips off the bandage at the back of his neck, the adhesive stinging because he just put it on today and it's meant to last several days. A wash of exasperation floods from him along with the sickly sweet pheromones that all omegas put out when their heat is coming.

People close enough to get a face full of it lean back but then rock forward unconsciously. A strong omega means more healthy babies which means they smell the best to potential mates. Mammon once described Reborn's scent as 'all the money'.

"There," Reborn deadpans. "Are we done now?"

Spanner looks curious. "Did Verde make you that cologne?"

"Ask him yourself," Reborn says, giving up. "No, wait. Verde – Verde, tell them I'm an omega. How many heats have I spent with you?"

Verde slides him a glance. "Two. Because you use Sun flames to speed through your heat unless you need to distract me with your scent to steal my things."

"You sound upset," Reborn points out. "You really shouldn't be upset when you have a sweet omega like me-"

"Sweet?" Verde spits out like a curse. He directs the rest to everyone else. "Reborn is only an omega when he needs to wield it like the weapon it is."

"But I'm still an omega," Reborn insists.

Tsuna looks a bit confused. "So you're like how Kyouya is technically a beta?"

Kyouya is a beta but everyone treats him like an alpha because he's got the instincts of one. Don't go into his territory without permission, don't touch the omegas he's marked, don't try and act dominant or he'll get aggressive, etc.

Reborn waves a hand vaguely through the air. "Sure, kind of like that."

"I still don't get the joke," Spanner admits.

Reborn takes a moment. "Fine. I'm an alpha."

Everyone immediately nods knowingly and makes agreeable sounds.

"I knew it," Byakuran says smugly.

**Notes for the Chapter:**

> Reborn gets pregnant and has a daughter but people still think this is some elaborate cosplay scheme.


	3. Like Sunshine

**Summary for the Chapter:**

> Tsuna never really understood the whole concept of smell and why so many other Omegas lost their minds. (And then Reborn regrows into an adult and presents as an Alpha.)

Tsuna is a very strong Omega at nineteen years old, both body and mind. He knows this very well because even with his so-so self-esteem he can actually smell how powerful he is.

If an Omega is stronger than an Alpha, the Alpha will smell dull. The personalised scent will be muted like how a beta will smell. The level of muteness depends on how big the difference in strength is - all so picking a mate is easier.

For instance, Spanner smells like almost nothing to Tsuna because while the mechanic has a strong mind, his body is average. Ryohei, who is incredibly strong but still quite a bit weaker that Tsuna, smells like something nostalgic - weak in memory but lovely all the same.

This scenting plays a big role in the world.

Small scented sachets of idols and celebrities will be bought online for thousands of dollars. At national sporting events the security measures involve dunking the athletes in a scentless bath to stop delirious Omegas from throwing themselves at the well-built competitors.

There are deodorants, medications, special clothing - both to dampen smell and to double it. The industry for this is worth the price of a small country.

In the Mafia, as always, everything is taken a step too far. The human trafficking rings all have a subsection dedicated to finding Alphas that smell mouth wateringly good.

An annual event where Omegas hunt down the best smelling prey has been set up since the eighteen-hundreds. Civilian Alphas smell weak, so all the attention falls on other mafioso, to the point where an Alpha is rare to find. In the Mafia, Omegas have hunted Alphas to near extinction.

That fact was a shock to Tsuna, who had grown up being taught that Omegas are frail and weak, always needing a big and strong Alpha to keep them safe and happy.

People even pointed at Kyouya back when they were young and whispered that an Alpha was going to come along one day and teach him to behave. What a joke! Tsuna would love to see someone try that rubbish.

Actually, never mind, Tsuna doesn't want to clean that up.

Tsuna presented midway through being sixteen, and even then he had gone through around three years of Reborn's daily training. He was strong enough that when he did start scenting Alphas, he still didn't understand why people went so crazy because nothing smelled so good that he'd lose his mind.

Tsuna...he understands now.

Reborn regrows to seventeen years old and presents as an Alpha during a trip to Mafia Land. Reborn smells like sunshine and chocolate, something rich and decadent.

Tsuna doesn't know how he makes it across the large donut pool, to where Reborn and Colonnello are huddled up and trying to slip away, but his mind is clear when he decks the motherfucker trying to grab Reborn, straight across the face with a right hook.

It's a man, another Don, and Tsuna gives no fucks. Bitch shouldn't have touched Tsuna's Alpha, okay?

And then Tsuna is knocking Reborn's hat away so he can stuff his face into the hitman's silky, soft hair and breathe in deep.

Tsuna blacks out then because Colonnello kicks him away and into the metal support strut of the giant waterslide.

Tsuna is told later, by Reborn himself, that the Arcobaleno quickly gave up trying to be subtle and just ran away. They had expected it but it happened too suddenly. They also sort of forgot how...enthusiastic people could get, because Reborn was stuck in baby form for so long.

Reborn has to go to ground for a while as Verde mixes up something that will withstand the hitman's Sun flames.

Reborn used to just straight up kill everyone that made a grab for him, right in broad daylight on the streets, and eventually people learned to stay away. Unfortunately, it's been a while, so the newer generation doesn't have that conditioned fear of Reborn - at least nothing strong enough to overpower his smell.

Tsuna now realises how blissfully ignorant he was before. Truthfully, most Omegas are weaker than an Alpha counterpart, so even someone who just exercises once a week smells heavenly enough to make an Omega dazed and desperate.

If Reborn doesn't take Verde's medication and walks down the street, he can actually knock people out cold just from his smell alone.

Tsuna turns into a disgusting freak for a couple of months after Reborn presents. He steals the hitman's used clothes and stuffs them into a pillow cover so he can be lulled to sleep by the smell of what seems to be lazy sex on warm days, but perhaps Tsuna is projecting.

Tsuna is not the only one who does this, which is good because Tsuna isn't as bad about it, but also he hates how people are trying to take away his hitman.

And yes, Reborn is Tsuna's hitman. They'll be together forever and Tsuna has already started planning the wedding and they'll have so many adorable babies together.

Then Reborn emerges, scent not quite muffled enough.

"I've been thinking," Tsuna muses, hands flat on his desk because he wants to touch but he's not allowed to. "We should really have better rules concerning the hunting and trading of Alphas. And considering my position of power, I have a responsibility to better our society."

Reborn is perched on a corner of the table, blatantly reading through secure files that no one but Tsuna should know about. He raises an eyebrow. "I can protect myself."

"It's not always about you, Reborn," Tsuna berates. "Honestly, the way people treat Alphas in the Mafia is atrocious. You can't just grab one off the street, consent is important!"

Reborn pauses. "I feel like civilian Omegas need your help more, considering they can't fight back like Mafia Alphas can."

"One thing at a time." Tsuna waves a hand dismissively and puts it down on Reborn's knee.

Reborn stares at the hand.

Tsuna takes it off.


End file.
